STEP ONE: Heat to sterilize the milk (185 degrees).
Put a washcloth, rag or dishcloth on the bottom of your big pot. Put the jars in and fill them with milk, leaving an inch or two at the top.
Fill the pot with water. Stop about 3/4 the way up the jars. Put your thermometer in the water to sterilize it. Bring the water to a boil. Once the water is boiling, move the thermometer to the smallest jar or the one with the least amount of milk. You can reduce the heat to medium-high.
Once the temperature of the milk reaches 185 degrees, remove the jar. The milk is now sterilized. If you have different sized jars or the jars contain different quanities of milk, move the thermometer to the other jars and remove them when the milk hits 185 degrees.
STEP TWO: Cool the milk (90-120 degrees).
Once the milk has hit 185 degrees it must be cooled to the incubation range. I put my jars in the kitchen sink filled with cold water. I also threw in a freezer pack to speed the process up. Again, I put the thermometer in the smallest jar.
After all the jars have been removed from the boiling water, put the lid on the pot and turn the heat off. Don’t dump the water. You will need it in the next step.
Remove the jar from the sink once the milk reaches between 90 and 120 degrees. It took about 12 minutes for my small jar and 16-20 for the bigger ones. If you miss the window and the milk gets below 90 degrees, just reheat it on the stove.
STEP THREE: Add yogurt starter.
When the milk has reached the incubation temperature window, add your yogurt starter. Add two tablespoons to a quart jar. Gently stir it. Immediately put the lid on the jar.
STEP FOUR: Incubate.
While your milk is cooling in the sink, get your cooler ready for incubation. Put a large bath towel on the bottom of your cooler with one end hanging out the side. Place the pot of hot water (lid on) on one side of the cooler.
When the jars are ready, place them next to the pot (not in it).
Once all jars are in their places, take the lid off the pot, wrap the towel around everything and close the cooler lid.
Now don’t mess with it. Seriously. Leave it alone.
Your yogurt will be ready in 4 hours, though you can let it incubate for up to 24 hours. I left my yogurt in the cooler overnight for about 10 hours and it came out perfectly. I did not add additional hot water.
This isn’t the greatest picture, but believe me, it’s yogurt. I put the jars in the freezer for an hour (Kitchen Stewardship said it improves the texture).
Now I can make yogurt at a fraction of the cost of store-bought! And it’s really easy. I did most of the steps with a fussy baby in one arm.